Regular faucet includes a draw-off tap, having a spherical portion on its casing with a valve stem vertically set therein, which valve stem comprises a conical valve cock at the bottom and a nut at the upper portion to fix on the casing for further revolving control through a setting knob to let the valve stem make up-and-down displacement. Through the displacement of the valve stem to provide space difference in cross-section inside the tap, the flow rate is accordingly controlled.
In the above-said faucet, the setting knob is fixedly attached to the valve stem at the top for revolving control to define a passage for water flow. After use, the setting knob is turned counter-clockwise to block water flow. This kind of conventional faucet is not specifically suitable for hand washing, since it has several drawbacks as hereunder.
&lt;1&gt; Unreasonable structure and easy to break down: In regular faucets, a valve cock is the member to stop water flow. The displacement of a valve cock is controlled by a revolving knob. Because the force applied from the person's hand to turn a valve cock varies with people, insufficient force may be available to screw up the valve cock tightly and may lead to water leakage, while excessive force applied to a valve cock may damage the valve cock and may lead to severe water leakage. More particularly, the inner thread of the casing and the outer thread of the valve stem are likely to wear out quickly to become unworkable.
&lt;2&gt; The regulating cock and switch control mechanism are incorporated together to cause waste of water. In regular faucets, the operating point is spaced away from the water spout. One is not washing one's hands while turning on the setting knob of a faucet to let water continuously come out. Because the regulating cock and switch control mechanism are incorporated together, it is more difficult to accurately control flow rate. It is more than embarrassing to adjust water temperature and flow rate from water faucets during the winter season. The complicated procedure may not only take a little bit of time but also cause waste of water.
&lt;3&gt; When to turn on a faucet to release water, the person's dirty hands will contaminate the setting knob. After washing of hands, the clean hands will be contaminated when the contaminated setting knob is turned off.
In general, regular faucets are not practical for use in washing hands. For washing hands, it requires a specific draw-off tap.